The present invention relates generally to an apparatus of surface grinding planar members, and more particularly, to an apparatus for surface grinding printed wiring boards for surface treatment thereof during their manufacture.
Conventionally, surface grinding of planar members is performed by a rotary brush or rotary stone. However, as the kinetic energy changes center portion to the peripheral portion of such a rotary brush, the ground surface can not be made uniform when the plane surface of such a tool contacts the planar member, and also, as the contact surface of the tool is too small when the peripheral surface thereof contacts the planar member, the ground surface also is not uniform.
To solve the above mentioned disadvantages, our Japanese Patent Application No. 62-283368, filed Nov. 10, 1987 and entitled "Method of Surface Grinding of Planar Member" discloses a method of surface grinding a planar member by a grinding tool which moves eccentrically on a plane.
All portions of the eccentrically moving planar tool, e.g. a brush, have the same kinetic energy, in contrast to a rotary brush, so that the same grinding effect is applied to the surface to be ground and a uniform ground surface can be obtained, and such results in uniform wear of the brush.
All grinding devices of the prior art perform only one function which is regarded as natural from the point of view of construction and purpose. However, when the quantity to be ground is very small, it is desirable to combine two grinding functions in one tool to perform continuously two functions by one process.